I haven't seen much of the genre but I've seen enough to know I don't like it. It's just not my thing. The only way I enjoy it is if it's like, extremely pardoied and stuff and doesnt take itself seriously at all.
Because people get tired of it, sooner or later. Right now people are suffering from the glut of comic films. At some point people got tired of western, alien, slasher, comedy and action films. Moderation is key to enjoying cinema too.I never understood the complaint that zombie/post apocalyptic stories specifically are "oversaturated" like it's somehow detrimental to the concept itself. What isn't oversaturated these days? Sci-fi? Fantasy? Superheroes? FPS? RPGs? Romantic Comedies? The list goes on and on. There's so many ways you can tackle a zombie apocalypse just like there's so many ways to approach any genre.
Speaking on games alone, we have stuff like Resident Evil, Dead Rising, Left 4 Dead, Days Gone, The Last of Us, Telltale's The Walking Dead, and House of the Dead. Yet, none of these games are even remotely similar and offer completely unique experiences from one another. It's a concept you either like or don't, just like RPGs/J-RPGs which I get tired of seeing flood gaming events because it's not for me, but it's great that people who like that sort of thing have so much of it to choose from.